We propose to study the effect of radio frequency irradiation on development of atherosclerosis in rabbits, rats, and squirrel monkeys. All animals will be fed an atherogenic diet and one group of animals will be irradiated while others serve as controls. After several months the animals will be sacrificed and their aortas will be analyzed for (1) the extent of intimal involvement in the atherosclerotic process (gross) (2) the extent of invasion of the media by foam cells (microscopic) and (3) the cholesterol content of the aorta wall. The effect of a range of frequencies between 10 to the 5th power and 10 to the 9th power Hz will be tested as will the effect of a range of field strengths between 0.5 and 50V/meter. To test the hypothesis that radio frequency irradiation causes arterial wall injury we will study the microscopic anatomy of the irradiated aortic wall in the absence of hypercholesterolemia. We will also study the effects of radio frequency irradiation on blood pressure and serum cholesterol concentration.